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WSPR problem - U3S
Nobody, including me can decode my WSPR signals on LF/MF and HF when I tx using 1) A U3S beacon and 2) A home made circuit based on an Arduino. Both transmitters used to get decoded OK. I have tested both in the shack and they seem OK to me. I can decode other people's WSPR signals just fine though on an IC-7300. My WSPR signal is decoded when using the IC-7300 as the transmitter on low power.
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The U3S gives about 313mW out on the 17m band. It draws 128mA not tx-ing and 250mA tx-ing.?
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My power supplies are a battery and linear types, I used a dummy load next to two receivers (dx394 and IC-7300) and pick up my weak signal but no decodes, and a loop antenna for outdoors, I use a GPS disciplined frequency source for the U3S and also a crystal control synth board, for the other I use crystal only. I use USB mode for Rx, no noticeable freq. drift using a GPSDO at 27MHz, GPS timing - spot on, recent Rx software.
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I can vary the Rx signal strength of my signals by repositioning the dummy load and get no decodes still be it weak or strong signals, I have set the Tx/Rx frequencies accurately and the Rx audio is in the centre of the expected range, I use a 100MHz bandwidth oscilloscope with an FFT feature to check the spectrum, at least for lower frequencies.
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I checked the look of the rx audio on Argo software the audio frequency deviation of 6Hz is correct. I use a nano VNA to check antenna impedance matching and get better that -10dB S11 which is OK. I have a low pass filter at the tx output for each band.?
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I went on air on several bands recently with my multi-turn loop antenna in the garden, it matches 50 Ohms well on nearly all the HF bands. I know the antenna works well with low power on 17m as the IC-7300 gets its WSPR tx decoded by others with 0% power setting.
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I have tried the U3S with a GPSDO and crystal types of 27MHz sources. The crystal one makes the U3S drift about 2-3Hz during transmission.
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These are the settings:
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3.12a 2017
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CW 10, Dit 006, Hel 000, speed -,?
Message - my callsign
Locator IO83CH
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Xw 0, X2 0, Tn 0, IV 0, TXS 8
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FSK 0, (fine Hz) 004
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Frame 04, Start 00
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GPS 1 (mode Baud) 009,600
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GPS 0 (Info, Check) 1
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Cal 02, (step, Time) 120
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Park 2, (Mode, Freq) 160,000,000
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PTT delay 000
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Shaping (ms 00, max 000)
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Sys Freq 20,000,000
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Ref Freq 27,003,288 (xtal synth)
27,000,001 (gpsdo synth)
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Bright 9, timeout 000
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Ftx 18,106,100
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The signal strength at the IC-7300 was S0, very weak but has additional lines at plus and minus N x 100Hz.
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There may be an additional issue related to this -?
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I have some power supplies, one a linear type (used in the tests above), one a switch mode type and the other is a car battery. I measured the AC (not DC) voltage across each and got 28.7V on the linear type, 29.1V on the filtered switch mode and 25.3V ac on the battery. Another DVM gave over 400Vac at times on the battery, fluctuating. Touching just the DVM lead gives 36mV ac. DC measurements are 11.9V battery, 13.6V switch mode supply and 13.3V linear supply. A scope probe on the linear one gives 62Vpp ac mains frequency, 50Hz UK (PSU on) and 7V ppk PSU off. Touching the scope probe tip gives 21Vpp ac. The mains ripple voltage superimposed itself on the measurement of power, above - Vrms measurement across the dummy load. Maybe the mains pick up affects the tx output spectrum, I listened on the IC-7300 and another receiver on AM mode and it doesn't have any buzzing sound though.
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I am puzzled as to why the signal is not decoded when using the U3S nor the home made circuit transmitters.
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Attachments - U3S-1/2 are screenshots of WSJT- and Argo for the GPSDO synth tests, U3S-c/d are of the xtal synth tests.
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Lucien
GW4SYI
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Re: QMX+ with ~1000 tone on 12M & 6M
I can hear the approx 1khz tone on all bands of my QMX+ v1.
Loudest on 12M and 6M, but to varying degree on all others.
Barely perceptible on 160M, but there.
It is not a 100% constant tone, there are small almost regular interruptions, as if digital and the breaks in the tone perhaps related to interrupt cycles(?). Beyond my knowledge base here…
Anyone else gone down the PCM1804 route as Jeff mentions and got a cure??
My radio appears to be working fine in all other respects.
I have built three QMX (mini) and not had any problems at all.
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Rowan.
G0KLH.
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Re: Best QMX AGC settings?
Hello Chuck ? Initially I tried both lower and higher AGC thresholds, and Did you try changing the other parameters other than AGC threshold?? I will look into it again when I have a chance; it has been a while since the AGC functionality was added and I get the impression generally most people think it is working well.? I think that there are settings which could cause it to be scratchy.? I do intend to create some "known good" settings to choose from to make it easy; leave the extensive full configurability in there for people who want it, but a few easy settings.? ? My SWAG on the problem is that the AGC routine's inputs The AGC action takes place AFTER the CW filter. If the crackling was generated by AGC that was ahead of the CW filter then the crackling would be filtered out by the CW filter...? ? I could not help but notice that many on this group speak Just enthusiasm, I suspect; most people here have had a lot of fun with the QRP Labs products. I am reading most of the posts here, I had not noticed people beating chests threateningly in regard to your questions.?? ? I meant no disrespect.? My feeling was that if others are No problem :-)? ?Nobody speaks on my behalf.? 73 Hans G0UPL |
Re: QMX+ 160m problems
Hi Dan,thanks for the suggestion, I will indeed try that next.
Hans diagnostic tools are great help with this sort of problem.
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While waiting for firmware to fix 160m problem is the bandpass filter response below typical ?
I will be doing Nicks suggestion around L401,C401.
73 Hugh GM8FXD
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Re: QMX, one of op-amps self-oscillates at 25 MHz (or picks up the system clock?)
I confirm that nothing should be writing to the '5351 during receive. Even during transmit, nothing should be causing interruptions at 100Hz. Makes no sense... I would suspect the '5351 chip...? 73 Hans G0UPL On Thu, Jan 9, 2025 at 8:05?AM Tony Scaminaci via <tonyscam=[email protected]> wrote:
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Re: QMX, one of op-amps self-oscillates at 25 MHz (or picks up the system clock?)
Adam, I think Jerry is on to something here. If I recall, Hans runs the I2C programming at 1 MHZ so your 200 is gap sounds like 200 bits are being written at an unwanted time and the 5351 stops clock outputs until programming is complete and the internal PLL relocks. Just a thought… Tony AC9QY On Wed, Jan 8, 2025 at 7:13?PM Jerry Gaffke via <jgaffke=[email protected]> wrote:
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New QMX+ build not powering up/accepting new firmware
Hello I have recently built a Rev 2 QMX+, for 9V. ? I am attempting initial power up with a 9V battery to see if LCD turns on or if I can update the firmware. I see neither the LCD screen go on, or see disk mounting actions to load the firmware. I tried different computers and USB-C cables. ? I touched up all soldering points, and don’t see anything physical wrong with the board. When I attempt power on (PWR/Vol knob) with a small amplified speaker connected I hear a loud click/thump. ? What would my first steps diagnosing potential issues be? ? Thank you. |
Re: audio volume QMX+
Charles
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Could it be your antenna is better on 40m?
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Could also be stronger signals then on 40m.?
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Try this. Find a spot on each band with no signals. See how the noise level varies across the bands.?
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Note the audio you hear is function of antenna behavior, it's matching and the qmx. Note when signals are present the AGC or lack of it can be very different than conventional receivers. Maybe all is actually okay. Signals were a bit strange today on the upper frequencies.?
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Curt
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Re: QMX Question for Troubleshooting
Don,
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Not sure why VDD would not be there with 9V applied to the input plug.? It works fine with only the control board plugged in and push on the left encoder to turn it on.? Then the USB port works fine.? If I had to guess, this is built into the the design to be able to test the main board independently during manufacturing.? It worked for me.? By all means, if your worried about hot unplugging the control board, don't.
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Brien |
Jeff Moore W1NC to the Repair Rescue
I wish to add my high praise and deep respect for Jeff Moore,? the skilled EE and repair wizard who's come to the rescue of so many of us kit builders with seeming impossible-to-fix radios.
A recent QMX+ kit shipment to me sustained a vertically crushed box by FedEx. The board inside appeared undamaged, so I carefully built the kit.? On completion, the radio was dead. Just inert. No smoke signals. Just dead.??
After exhausting all my knowledge in trying to bring it to life, I concluded that the board or one or more components were damaged by the shipper.
So I sent it to Jeff Moore, who took on the task.? Without going into deep detail, suffice it to say that the challenges it presented may well have been among the toughest anyone could remotely imagine.
After hours upon hours of work, consultation, repair and replacement of multiple major components, some more than once, Jeff has been able to bring my radio back from the dead.?
As many know, Jeff is a generous community resource whose value cannot be over-stated.? He does not charge a fee for his efforts -- only asks help paying for parts used, postage, and a voluntary donation to a funds pool to help others, if one is so motivated.??
So if you ever want to give up on a radio, don't.? Contact Jeff and ask if it's OK to send it to him for evaluation.
Thank you, Jeff.
72 and 73,
Bill Jobes? W3WJ??
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